The early events of looping (rotation and bending) of the embryonic vertebrate heart are deformations. The deformative forces and their regulation are intrinsic to the heart. A model of cardiac morphogenesis is described in this paper. It is proposed that synthesis of extracellular matrix by the myocardium generates an internal pressure. This pressure acts as a deforming force on the myocardium which controls strain by regulating compliance. This model provides an explanation of cardiac morphogenesis at the biochemical and biomechanical levels.